ABSTRACT: Colonoscopy affords the opportunity for detection and removal of polyps and thus can prevent the development of colorectal cancer (CRC). Colonoscopy is not an unlimited resource. Its appropriate utilization is critical to optimizing CRC screening. Wide variations exist in colonoscopy practice and outcomes. Understanding these variations and the factors contributing to the most effective and efficient outcomes would inform appropriate CRC screening in both community and academic settings. Through this innovative project we will characterize colonoscopy practices, outcomes and their variations for the New Hampshire (NH) adult population by expanding the NH Colonoscopy Registry to include a high proportion of NH colonoscopists, linking colonoscopy findings with patient factors and pathology results. This characterization will be dynamic, addressing current practices and how practices evolve over time including the impact of emerging technologies such as CT colonography and fecal DNA analysis. As findings accrue, we will explore their implications with key stakeholders leading to better understanding and to future quality improvement and research projects that improve the provision of colonoscopy to control CRC. This work is informed and inspired by work of population-based mammography registries over the past decade. One of these, the NH Mammography Network, will provide proven methods, practical experience, and a record of productivity to this project. The NH Mammography Registry principal investigator and staff play active and substantial roles in this new work on colonoscopy. Project aims include: AIM 1: To identify polypectomy rates, types of polypectomies, pathology findings, completion rates, and complications for screening, surveillance, and diagnostic colonoscopy, including adjustment for patient risk factors, using a state-based colonoscopy registry. AIM 2: To examine discrepancies between colonoscopists'recommendations for timing of repeat exams and recognized guidelines for specific patient subgroups. AIM 3: To identify sources of variation identified in Aim 1 and Aim 2, including the degree to which patient, colonoscopist, and practice setting factors contribute and have the potential for modification. AIM 4: To share findings from Aims 1-3 with key stakeholders (colonoscopists, primary care clinicians, and community members), explore their views on the implications of these findings, and develop insights on opportunities for intervention that could be addressed in subsequent proposals. AIM 5: To explore the impact of emerging technologies on colonoscopy as applied in both academic and community-settings. PROJECT NARRATIVE: Relevance: Colorectal cancer is a major killer and colonoscopy is currently our best defense. Inspired and informed by the progress against breast cancer that has resulted from population- based mammography registries, this project will create a colonoscopy registry to advance our understanding of how it is provided in representative community and academic settings, the outcomes it currently achieves, and how the practice evolves as technology advances. To spur innovations, physician and community stakeholders will be engaged in interpreting the findings and developing actions needed to increase its quality and appropriate use.